1. Field of the Invention
The present invention relates to a digital video apparatus which is capable of transferring and receiving digital video data.
2. Related Background Art
The IEC 61883-4 is a standard that defines a protocol for transferring a transport stream (TS) packet of MPEG-2 using isochronous transfer prescribed by the IEEE Std 1394-1995. According to the IEC 61883-4, a TS packet should be transferred using a common isochronous packet (CIP) header prescribed by the IEC 61883-1.
Note that the IEEE Std 1394-1995 is described in detail in “IEEE Std 1934-1995, IEEE Standard for a High Performance Serial Bus”, Institute of Electrical and Electronics Engineers, Inc. The IEC 61883-1 is described in detail in “IEC 61883-1, Consumer audio/video equipment—Digital interface—Part 1: General”. In addition, the IEC 61883-4 is described in detail in “IEC 61883-4, Consumer audio/video equipment—Digital Interface—Part 4: MPEGS2-TS data transmission”.
However, the IEC 61883-1 and the IEC 61883-4 do not prescribe in their specifications that a transmission source apparatus (an apparatus that reproduces digital video data from a storage medium and transfers the digital video data being reproduced, an apparatus that records digital video data in a storage medium and transfers the digital video data being recorded, or the like) should notify a transmission destination apparatus of an operation state (whether or not the apparatus is reproducing data, whether or not the apparatus is recording data, whether or not the apparatus is suspending recording or reproduction of data, a playing direction, a playing speed, and the like) of the transmission source apparatus by using a CIP header.
Therefore, the conventional transmission source apparatus has a problem that it cannot notify the transmission destination apparatus of an operation state of the transmission source apparatus unless a special command is used. In addition, the conventional transmission destination apparatus has a problem that it cannot learn of an operation state of the transmission source apparatus unless a special command is used. It should be -noted here that such a problem exists not only in the case in which digital video data encoded into a TS packet of MPEG-2 is transferred but also in the case in which digital video data is transferred using a data header such as a CIP header.